BALTIMORE — Republican congressional leaders said Friday that they were moving aggressively to draw up a campaign platform for 2016 so that the party would be positioned to coalesce swiftly around a nominee after a bruising primary campaign.

After a three-day retreat here, House Republicans emerged with a plan to attack five policy areas — national security, the economy, health care, poverty and the Constitution — but stopped short of promising legislation on any of them.

The House will set up committee task forces to complete a policy agenda “by the time we have a nominee,” Speaker Paul D. Ryan said during a brief news conference Friday afternoon after numerous policy sessions, some of them with Senate Republicans. Calling 2016 a “generational defining moment,” Mr. Ryan said congressional Republicans would set the policy template for the campaign. “The country is crying out to be unified,” he said.

Mr. Ryan and other Republican leaders insisted repeatedly that they had not discussed the race for the White House during their numerous policy sessions; Mr. Ryan and others said they did not even watch the debate Thursday night. Many members opted instead to go to a screening of a new film about the Benghazi, Libya, attack.

Privately, however, congressional Republicans repeatedly acknowledged their panic over the increasingly nasty primary race, and particularly the bombastic rhetoric of Donald J. Trump, who they fear could pose a risk of splintering the party and alienating voters. Some were equally worried about the rise of Senator Ted Cruz, Republican of Texas. “I think Marco Rubio is the right face and the right voice for the Republicans,” said Representative Bill Huizenga, Republican of Michigan. “Cruz is just a little more edgy. I find Marco more optimistic.”

House Republicans seemed eager to get behind Mr. Ryan’s agenda and to try to reset the tone of the campaign. “The presidential candidates are speaking in one-minute sound bites and really not saying anything,” said Representative Devin Nunes, Republican of California and chairman of the House Permanent Select Committee on Intelligence.

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Many Republicans in Congress said they were worried about the rise of Donald J. Trump and Senator Ted Cruz because they could splinter the party and alienate voters.CreditEric Thayer for The New York Times

But the only area where House and Senate Republicans promised legislation was appropriations. It was unclear, for instance, whether Republicans will actually present a plan to replace the current health care law that has been their central policy punching bag since they took over the House.

Republican leaders in the House and Senate demurred on whether they would write and vote on a bill this year. But members were concerned by a presentation of polling data, some Republicans said, that found that while the health care law remained unpopular with many people, Democrats had a double-digit lead over their party on the issue of health care.

Mr. Ryan’s determination to have a strong platform in place by the time a Republican candidate is chosen might also reflect his own personal assessment of the 2012 presidential contest, after he was on the losing ticket as Mitt Romney’s vice-presidential nominee. Mr. Ryan on several occasions has said that Republicans came up short in providing voters with a sufficient enough contrast between their priorities and the policy goals of President Obama.

Acknowledging the reality of the polls and the discipline that has historically been the spine of their party in an election year, Republican leaders made it clear they would support whoever ends up at the top of the ticket.

Senator Mitch McConnell, Republican of Kentucky and the majority leader, and Mr. Ryan said that any of the Republicans on stage, including Mr. Trump, would be a better choice for the country than either of the leading Democrats, Hillary Clinton and Senator Bernie Sanders of Vermont.

“I’m excited about our field,” said Representative Steve Scalise of Louisiana, the No. 3 House Republican. “Whoever comes out of our field is going to be able to unite our party and is going to be able to win in November, because the contrast is going to be somebody who is fighting over who’s more socialist, Bernie Sanders and Hillary Clinton. And our country’s not a socialist nation.”

Mr. Ryan also seems to be having a long honeymoon with the more restive conservatives in his conference. His presentation to members Wednesday night on their agenda received a “huge standing ovation,” Mr. Nunes said. “It was by far the best political speech by any member of the House or Senate I’ve ever seen,” he said.

A version of this article appears in print on , on Page A13 of the New York edition with the headline: Republicans in Congress Will Write the Platform for the 2016 Campaign, Ryan Says . Order Reprints | Today’s Paper | Subscribe